Postal workers get through two million red rubber bands per day, the Royal Mail has revealed.
In the past five years, the organisation has spent almost £5m on four billion bands which are used to bundle letters together.
Keep Britain Tidy has called for their use to be reduced because they say wild animals can choke on them.
The Royal Mail says the bands are necessary and that they use biodegradable ones.
The figures were released to the Daily Telegraph under the Freedom of Information Act.
It said that the amount the postal organisation spends on bands has increased by 40% in five years.
Keep Britain Tidy has long campaigned against the use of rubber bands.
In 2009, about 13,000 discarded bands were collected by people and sent in to the charity who then delivered them to the Royal Mail's headquarters.
Dickie Felton, from Keep Britain Tidy, has previously said: "We accept that dropping an elastic band is hardly the worst littering offence in the world, but none-the-less it is litter.
"The bands look terrible strewn on the floor and pose a choking danger to pets and wildlife."
A Royal Mail spokesman said: "Royal Mail regularly reminds postmen and women about the importance of avoiding litter.
"The vast majority of rubber bands are re-used by our people in delivery offices and mail centres across the UK."